The present invention relates to a ventricular assist pump. It relates for example to a pump supplied by battery and intended to be inserted into a human body in order to help blood circulation.
In the field of ventricular assist systems, two types of pump are known: the axial pump, which generates a high flow rate with a small pressure increase, and the centrifugal pump, which generates a high pressure with a low flow rate.
In order to determine which type of pump is the most suitable for a given use, it is often necessary to estimate a specific speed of the blood in the pump. The specific speed is a standardized variate calculated as a function of different parameters: the desired flow rate, the elevation height (difference in pressure between the inlet and the outlet) and the speed of rotation. Starting from this value, the pump can be chosen from the following types: centrifugal for a speed comprised between [0-1.2], mixed-flow for a specific speed comprised between [1-2.2] and axial above. Nomograms make it possible to choose a type of pump with a predefined profile for the wings or blades used in the rotor.
Regardless of the type of pump chosen, the presence of shear stress is observed in most of the pumps of the prior art, due to the fact that the rotors and casing used in the prior art create excessive vortices in the blood. Shear stress can result in hemolysis, i.e. the destruction of red blood cells. When red blood cells are destroyed, oxygen does not reach the cells, regardless of the flow rate at which the blood is conveyed.
Another drawback is the stagnation of blood causing blood clots, leading to thrombosis.
A subject of the present invention is a pump that avoids producing thrombosis.
Another subject of the invention is to avoid producing hemolysis.